The present invention concerns jacquard mechanisms for knitting machines, of the type comprising a set of jacquard-mechanism jacks whose positions are determined by a pattern-data storage, with the jacquard-mechanism jacks controlling needle operation through the intermediary of a pattern wheel or else operating directly on the butts, jacks or pattern bolts of individual needles.
Federal Republic of Germany patent DE-PS No. 1,044,337 discloses a jacquard mechanism in which the positions of the jacquard-mechanism jacks are determined by a jacquard card, with the jacquard-mechanism jacks in turn establishing the positions of jacks of a pattern wheel. Because the mechanism is entirely mechanical in operation and relies upon the use of jacquard cards, considerable limits are placed upon the speed of operation of knitting machines controlled by such jacquard mechanism.
Accordingly, Federal Republic of Germany published patent application DE-OS No. 1,585,078 proposed the selection of the positions of the jacquard-mechanism jacks by electromagnetic means. This jacquard mechanism is provided with a set of angled levers pivotable about a shaft with each lever provided with a respective electromagnet. After the desired angled levers have been moved to selected position, the entire jacquard mechanism is moved as a unit into engagement with the butts to be controlled. This mechanism requires electromagnets capable of developing rather sizable magnetic attractive forces, and therefore considerable amounts of energizing current, which are required to move the angled levers from one to another position against the force of associated biasing springs. Especially where high fabric finenesses and small interneedle spacings are involved, it becomes difficult to provide electromagnets of sufficiently great attractive power in the very limited space available for each one. Furthermore, because the jacquard mechanism must be shifted as a whole into engagement with the butts to be controlled after the angled levers have been set to their selected positions, considerable limits are, here likewise, placed upon the speed of operation of the knitting machine controlled by such system.
Finally, Swiss patent CH-PS No. 517,855 discloses a mechanism in which each knitting needle is provided with a separate magnetic actuator unit of its own, comprised of a detector, a level detector circuit, a monostable circuit, a permanent magnet and a flux-reversing winding operative for reversing the permanent magnet's flux in dependence upon the output pulse produced by the respective monostable circuit. The selection of individual knitting needles is performed via a patterning rocker mounted in the needle bed and activatable by the armature of the respective permanent magnet.
Selected permanent magnets are caused to undergo a direction-reversal of their magnetic flux which releases their armatures for needle-selecting action. The armatures of the non-selected permanent magnets are then pulled back. This system has the clear disadvantage that it requires a considerable number of electronic components for each individual knitting needle, and therefore is very costly to manufacture and assemble. The large number of components needed furthermore increases the system's susceptibility to malfunction and thus involves high maintenance costs. Furthermore, the replacement of individual, malfunctioning components is complicated and requires skilled personnel. Above all, the construction of such system does not provide for or lend itself to quick-assembly modular configuration such as could permit quick assembly of modular components for differing finenesses of fabric to be produced on a cooperating knitting machine.